scsi: ufs: core: Fix a race condition related to device management

scsi: ufs: core: Fix a race condition related to device management

If a device management command completion happens after
wait_for_completion_timeout() times out and before ufshcd_clear_cmds() is
called, then the completion code may crash on the complete() call in
__ufshcd_transfer_req_compl().

Fix the following crash:

  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
  Call trace:
   complete+0x64/0x178
   __ufshcd_transfer_req_compl+0x30c/0x9c0
   ufshcd_poll+0xf0/0x208
   ufshcd_sl_intr+0xb8/0xf0
   ufshcd_intr+0x168/0x2f4
   __handle_irq_event_percpu+0xa0/0x30c
   handle_irq_event+0x84/0x178
   handle_fasteoi_irq+0x150/0x2e8
   __handle_domain_irq+0x114/0x1e4
   gic_handle_irq.31846+0x58/0x300
   el1_irq+0xe4/0x1c0
   efi_header_end+0x110/0x680
   __irq_exit_rcu+0x108/0x124
   __handle_domain_irq+0x118/0x1e4
   gic_handle_irq.31846+0x58/0x300
   el1_irq+0xe4/0x1c0
   cpuidle_enter_state+0x3ac/0x8c4
   do_idle+0x2fc/0x55c
   cpu_startup_entry+0x84/0x90
   kernel_init+0x0/0x310
   start_kernel+0x0/0x608
   start_kernel+0x4ec/0x608

Link: https://lore.kernel.org/r/20220720170228.1598842-1-bvanassche@acm.org
Fixes: 5a0b0cb9bee7 ("[SCSI] ufs: Add support for sending NOP OUT UPIU")
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Avri Altman <avri.altman@wdc.com>
Cc: Bean Huo <beanhuo@micron.com>
Cc: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>